<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js---七大数据类型测试</title>
    <style>
        .container{
            display: flex;
            margin: 0 auto;
            width: 1000px;
        }
        .container div{
            margin:0px 10px;
            background-color: skyblue;
            text-align: center;
            cursor:pointer;
            padding: 5px 20px;
            border-radius: 5px;
            color: hotpink;
            font-weight:bold;
        }
        .container div:hover{
            background-color: green;
        }
    </style>
</head>
<body>
    <div class="container">
        <div>Undefined</div>
        <div>Null</div>
        <div>Boolean</div>
        <div>Number</div>
        <div>String</div>
        <div>Symbol(es6新增的一种)</div>
        <div>Object</div>
    </div>
    <script>
       
        // 对于未定义的变量，返回undefinedm
        console.log(typeof age);
    </script>
</body>
</html>